In Barbour’s universe, every moment of every individual’s life— birth, death, and everything in between— exists forever. “Each instant we live,” Barbour says, “is, in essence, eternal.” That means each and every one of us is immortal. Like the perpetually unmoving lovers in Keats’s “Ode on a Grecian Urn,” we are “for ever panting, and for ever young.” We are also for ever aged and decrepit, on our deathbeds, in the dentist’s chair, at Thanksgivings with our in-laws, and reading these words.
Barbour’s central argument is that a mistaken belief in the reality of time prevents physicists from achieving their ultimate goal: the unification of the submicroscopic atomic world of quantum mechanics with the vast cosmic one of general relativity. The problem arises because each theory provides a radically different conception of time, and physicists simply don’t know how to reconcile the two views. Until they do, they will never have one seamless theory of the universe comprising the very smallest objects to the very largest. And certain middling-sized objects— human beings— will never understand the true nature of time and existence.
What makes the two versions of time so different? Time in the quantum realm has no remarkable properties at all. In theories of quantum mechanics, time is essentially taken for granted; it simply regularly ticks away in the background, just as it does in our own lives. Like a clock at a sporting event, it provides an invisible framework in which events unfold. That’s not the case in Einstein’s general theory of relativity.
To describe the universe on the largest scale, Einstein had to weave time and space together into the very fabric of the universe. As a result, in general relativity, there is no invisible framework, no clock ticking outside the universe against which to measure events. How could there be? Time and space joined together have weird consequences: Space and time curve around stars and other massive bodies and make light bend away from straight-line paths. Near black holes, time seems to slow down or even come to a full stop.
Barbour is not alone in recognizing that the pictures of time in general relativity and quantum mechanics are fundamentally incompatible. Theoretical physicists around the world, spurred by Nobel dreams, sweat over the problem. But Barbour has taken perhaps the most unorthodox approach by proposing that the way to solve the conundrum is to leave time out of the equations that describe the universe entirely. He has been obsessed with this solution for more than 10 years, since he learned of a vexing mathematical tour de force by a young American physicist named Bryce DeWitt.
DeWitt, with the help of the eminent American physicist John Wheeler, developed an equation in 1967 that apparently melded quantum mechanics with general relativity. He did this by taking the principles from quantum mechanics that describe the interactions of atoms and molecules and applying them to the entire universe, a mind-bending feat not unlike trying to make a jockey’s suit fit Michael Jordan.
Specifically, DeWitt hijacked the Schrödinger equation, named for the great Austrian physicist who created it. In its original form, the equation reveals how the arrangement of electrons determines the geometrical shapes of atoms and molecules. As modified by DeWitt, the equation describes different possible shapes for the entire universe and the position of everything in it. The key difference between Schrödinger’s quantum and DeWitt’s cosmic version of the equation— besides the scale of the things involved— is that atoms, over time, can interact with other atoms and change their energies. But the universe has nothing to interact with except itself and has only a fixed total energy. Because the energy of the universe doesn’t change with time, the easiest of the many ways to solve what has become known as the Wheeler-DeWitt equation is to eliminate time.
Every Now is a complete, self-contained, timeless, unchanging universe. We mistakenly perceive the Nows as fleeting, when in fact each one persists forever. Because the word universe seems too small to encompass all possible Nows, Barbour coined a new word for it: Platonia. The name honors the ancient Greek philosopher who argued that reality is composed of eternal and changeless forms, even though the physical world we perceive through our senses appears to be in constant flux.